1. Field of the Invention
The invention relates to a method for managing a power system of a PDA, and more particularly, to a method for switching the PDA among SHUTDOWN mode, ON mode, SCREEN TOGGLE mode, and STANDBY mode to manage the power system of the PDA.
2. Description of the Prior Art
Nowadays, low-polluting electric power applications are advocated and many electric appliances use electric power to operate. A reduction in the volume and the weight of electric appliances makes the appliances more convenient and portable. A PDA (Personal Digital Assistant) is a portable and popular device and can allow users to manage their schedules and to store data. Compared with a desktop or a notebook, it is more convenient for users who have to deal with computer data mobilely like sales and on-line production managers. Like other portable electric appliances, a battery is the main power supply source in the PDA, but the volume of the battery is limited in a PDA. A power control system can alert users to the exhaustion of the volume of the battery and allow users to control the consumption of the volume of the battery. For instance, users can store data, change another battery, or recharge the PDA using an external power supply before the exhaustion of the battery so that data is not lost or so that damage does not occur in the PDA due to over-discharging. In view of the above, an effective and perfect power control system is emphasized in modern industry.
To reduce the power consumption of a PDA in the present power control system, the power supply of the electric component can be cut or reduced when the system is in an idling state. The power control system in the PDA is capable of detecting whether input buttons, display devices, and other components are switched on. If the power control system does not detect any activity during a certain period, the power supply of the main system will be shut down temporarily. However, in the prior art, the power management of the PDA is usually mainly controlled by the CPU, and the feasibility of using the microprocessor to control the power management of the PDA is neglected. Therefore, besides consuming a lot of system resources, the prior art method is dangerous because the large power consumption of using the CPU to control the power management of the whole system could result in over-discharging. In addition, the most power-consuming part of the PDA is the display panel. The prior art usually neglects to consider the power consumption of the display panel when utilizing the power management of the PDA so that the danger of over-discharging still exists. To solve the above-mentioned problems, first, not only can the technology of the prior art pertaining to the power control system of the microprocessor be utilized, but also the microprocessor can be used to supervise the whole power control system in the PDA. Besides, the display panel and other related peripherals should be taken into consideration of the power management of the PDA.